Recently, in dialysis apparatus used as a blood purification apparatus, a technique has been suggested that performs priming, reinfusion, and fluid infusion (emergency fluid infusion) using a dialysate supplied to a dialyzer during dialysis treatment (particularly, an on-line HDF or an on-line HF). For example, Patent Document 1, Japanese Laid-Open Patent Publication No. 2004-313522 discloses a dialysis apparatus that includes a fluid infusing line that has one end connected to a collection port formed in a predetermined part of a dialysate introduction line. The other end is connected to a blood circuit (arterial blood circuit or venous blood circuit). A fluid infusing pump is disposed in the fluid infusing line. In order to perform priming, the reinfusion or the fluid infusion (the emergency fluid infusion) using the dialysis apparatus, the dialysate in a dialysate introduction line is supplied to the blood circuit (the arterial blood circuit or the venous blood circuit) by driving the fluid infusing pump.
However, in a blood purifier, hereinafter called an on-line HDF that is applied to the blood dialysis filtration (HDF) and uses the dialysate as the fluid infusion, there is a need to perform the fluid infusion, including a pre-fluid infusion performing fluid infusion by the arterial blood circuit and a post-fluid infusion performing fluid infusion by the venous blood circuit, of the dialysate to the patient's blood by the ultrafiltration corresponding to a filtration treatment as the HDF treatment. An apparatus applied to the on-line HDF, is disclosed in Japanese Laid-open Patent Publication No. 2001-112863. Here, a dialysis apparatus has been suggested that has a dialyzer, a blood circuit, a dialysate introduction line, a dialysate discharging line and a fluid infusing line. The blood circuit includes an arterial blood circuit and a venous blood circuit with a blood pump. The dialysate introduction line introduces the dialysate into the dialyzer. The dialysate discharging line discharges the dialysate from the dialyzer. The fluid infusing line (a pre-fluid infusing line or a post-fluid infusing line) supplies the dialysate, of the dialysate introduction line, to the blood circuit to perform the fluid infusion without going through the dialyzer.